A 16S rrn dendrogram of clostridial species. The 16S rrn genes from the 15 strains examined in this study (13 C. botulinum indicated in red, one BoNT/E-producing C. butyricum in red and one C. sporogenes in blue) were aligned to the 16S rrn genes of different Clostridium species identified within Genbank via BLAST searches. A maximum likelihood tree using 78 sequences with four outgroup sequences from the Alkaliphilus genus (removed) was generated from 1,208 nucleotides. The scale bar of 0.03 represents three point mutations per 100 bases or 3% diversity between sequences. Two 16S rrn gene sequences from C. sporogenes ATCC 15579 are included. The 16S rrn dendrogram illustrates the genetic diversity within the Clostridium genus and among strains within the Group I-VI designations.